Excavating machines, backhoes, etc. have a large articulated working arm with a tool attached to the free end of the arm. For example, a bucket may be attached to the arm, or a heavy chisel or hammer may be attached to the arm. Because of the great weight and size of the tools, it is difficult and cumbersome to change from one type of tool to another tool to be mounted on the arm.
Normally a tool is attached to the free end of the articulated arm by means of two heavy pins which must be inserted through registering openings in the arm and the tool. This is difficult and cumbersome. It can also lead to injury to the workmen involved in handling the large pins.
Although a number of hitch or coupling assemblies have been described for connecting a tool to the end of a working arm, none of such assemblies has been entirely effective. In U.S. Pat. No. 4,881,867 (Essex) there is described an attachment device with a pair of jaws, with one of the jaws being hydraulically movable between an extended and a retracted position. The jaws are intended to engage the transverse hinge pins of a bucket, hammer, or other tool. The disadvantages of this type of attachment device include the fact that a hydraulic line could become damaged or otherwise rendered inoperative so that the movable jaw may move to its retracted position while the apparatus is being used. As a result, the tool attached to the end of the working arm may come loose. This could cause damage to the tool or other property or could even result in personal injury if the tool should happen to fall on someone. Also, if the hydraulic cylinder is not completely extended to connect the fingers to the pin, a dangerous situation could be presented because the fingers could slip off the pin.
In U.S. Pat. No. 4,810,162 (Foster) there is described an attachment device also having a pair of jaws. One of the jaws is fixed and the other is hinged and can pivot between open and closed positions. The jaws are for engaging the hinge pins of a bucket or tool. A spring biases the movable jaw to its open position. A latch retains the movable jaw in a locked position.
Because of the offset pin locations used in the attachment device, the tool which is attached to the end of a working arm is closer to the operator than is desired. As a result, the operator cannot see the lock because he is on the opposite side of the working arm. Thus, the operator has no way to assure that the lock is properly applied or in its fully-latched position. Consequently, if the lock is not completely latched, the movable jaw could come loose during use of the equipment. This could result in loss of the tool during operation, leading to property damage or personal injury.
In U.S. Pat. No. 5,082,389 (Balemi) there is described a connecting device for implements and it includes a fixed jaw and a hydraulically-operated closure member. The disadvantages of this type of connecting device include those described above with respect to the Essex patent.
U.S. Pat. No. 4,726,731 (Jones) describes a quick release hitch which includes a pair of pivoting jaws for engaging the hinge pins of an implement. Both of the jaws must be pivotably moved with a linkage system in order to engage the hinge pins. The disadvantages of this device include those described above with respect to Essex patent.
U.S. Pat. No. 4,013,182 (Pratt) describes a detachable coupling system for attaching an implement to a prime mover. The system includes a collapsible assembly having transverse bars which can be moved toward each other or away from each other. The implement includes spaced-apart hook members which are engaged by the transverse bars when the bars are moved apart from each other. The main disadvantage of this coupling system is that it would not be suitable for coupling an existing bucket or other tool to the free end of a working arm.
U.S. Pat. No. 1,429,389 (Weintz) describes a gate latch which includes pivoting latch members which engage a gate post and may be locked in a closed position. Such disclosure does not teach anything in regards to attachment systems for connecting a tool to the free end of a working arm.
There has not heretofore been provided a simple and effective coupling system for detachably connecting a tool to the free end of a working arm having the advantages of the present invention.